From today’s New York Times, in a death notice, “Yoko Nagae Ceschina, Countess and Fairy Godmother to the Arts, Dies at 82″ by Margalit Fox:
I used to play 120 concerts a year,” [the violinist Maxim Vengerov said. “She would follow me — not to all of the concerts, but to the most important ones, which were probably about 80 or so. I would go to Chicago; she would be there. I would go to Japan; she would turn up there. Then she finally announced that she would like to be my grandmother.”
And so, in effect, she became, on one occasion flying to Switzerland to bring Mr. Vengerov, ill with pneumonia in a hotel room there, an immense fur coat.
The crucial bit is boldfaced.
I read this at first as an anaphoric ellipsis of the complement of became (with so as a sentence-introducing adverb: ‘as a result, consequently’). Then it occurred to me that the so might have been intended as the complement of became: ‘that she became, she became that (i.e., his grandmother)’. The first structure is just impossible for me, and the second is very awkward.